British-only passport holders cannot audition for part of Prince William in new Princess Diana film

British actors will be banned from from auditioning to play Prince William in a new film because of restrictions when the UK separates from the EU in January.

A casting note issued on the part for a boy to play William aged 11 in the upcoming movie Spencer says British-only passport holders need not apply.

The note says only European passport holders will be eligible “due to new Brexit rules from 1st January 2021”.

Amy Hubbard, the casting director on the film, said it was not unusual for key actors to be required to share citizenship with the finances of the production.

The film, which is scheduled to begin in mid-January, stars Kristen Stewart as Princess Diana in the film.

It will tell the story of a weekend in the early 1990s when Diana decided her marriage to the Prince of Wales was failing.

Stewart, 30, told Jimmy Kimmel that while she was “really young” at the time of Diana’s death, after researching the royal’s life she feels more “protective.”

“I was really young when she passed away,' Stewart said. “It happened really quickly.

“I was really young, [I] didn't know what was going on,” she said adding she found it “hard not to feel protective of her.”

“She was so young.”

Speaking in detail about the film, the actor said: “My movie takes place over three days, and it's this really poetic internal imagining of what that might have felt like rather than giving new information.”

Twilight star Stewart has previously said playing such a well-known figure had been “intimidating.”

She told InStyle earlier this year: “The accent is intimidating as all hell because people know that voice, and it’s so, so distinct and particular. I’m working on it now and already have my dialect coach.

“In terms of research, I’ve gotten through two and a half biographies, and I’m finishing all the material before I actually go make the movie.

“It’s one of the saddest stories to exist ever, and I don’t want to just play Diana – I want to know her implicitly. I haven’t been this excited about playing a part, by the way, in so long.”

Emma Corrin, 24, is currently playing Diana in Netflix’s fourth series of The Crown.